A microphone captures an incoming sound wave as a vibration of a diaphragm and converts the vibration into an electric signal. For example, when a sound is picked up outdoors, the diaphragm is vibrated by a wind and wind noise is generated. In the case of a vocal microphone, when “p” or “t” is sounded from lips, the diaphragm is strongly vibrated by a sound pressure and a pop sound is generated.
Thus, for a microphone used for picking up a sound outdoors or near a mouth, a wind shield is frequently used to reduce the occurrence of wind noise. In many cases, an open-cell foam such as a urethane foam is used for the wind shield.
There are many patterns of wind shields. As an example, Patent Document 1 (Japanese examined utility model application publication No. H01-34470) proposes a wind shield made of a single material. The wind shield is entirely formed as a single-piece construction of an open-cell foam. Further, Patent Document 2 (Japanese Patent Application Publication No. S59-146294 proposes a composite (dual) wind shield which is a combination of a first foamed resin wind shield and a second foamed resin wind shield.
In the case of the wind shield made of a single material described in Patent Document 1, an air layer formed of a notched portion is provided as a solution to pop sound. However, a certain size is necessary to obtain a practical effect, so that it is difficult to meet the need for miniaturization.
According to the composite wind shield described in Patent Document 2, it is possible to select and combine materials in consideration of the frequency response of a microphone. However, since the wind shield is entirely housed in a guard mesh (a wind shield of a wire net), a replacing operation for changing combinations of materials is difficult. In addition, the guard mesh acts as the housing case of the wind shield, and thus the wind shield cannot be applied to a microphone having no guard mesh.